Hydrogen fluoride, also known as hydrofluoric acid, is used to raise the octane on gasoline at 50 refineries around the country, including Husky’s facility in Superior. It’s the most dangerous chemical handled in the Twin Ports, and emergency planning for the refinery is based on the worst-case scenario of a massive, sudden release that could affect up to a 25-mile radius.

There are safer alternatives to hydrogen fluoride, but it could be difficult and costly to switch to the other common catalyst, sulfuric acid. It would also take years, meaning hydrogen fluoride is here to stay barring any sudden moves or the discontinuation of gasoline production by Husky.

A Chevron refinery in Salt Lake City is implementing a new alternative called ionic fluids, which will completely replace the hydrogen fluoride the company has long used. Distributor Honeywell said refineries are in “wait-and-see mode” before making their own investment in the technology.

Since 1987, accidental hydrogen fluoride releases at refineries around the country have caused injuries but no deaths, and there is no record of a significant release at the Superior refinery. Even as the April 26 fire raged within sight of 15,000 pounds of hydrogen fluoride, the chemical was kept safe, as the refinery assures it will continue to be.

A total of seven facilities around the Twin Ports handle toxic chemicals that pose a risk to nearby residents under extremely unlikely though technically possible worst-case scenarios. After hydrogen fluoride, a potential chlorine release at Cloquet Pump Station No. 2 and a possible propane explosion at a Superior storage facility put the most people at risk. Western Lake Superior Sanitary District eliminated one of the greatest worst-case risks when it abandoned the use of chlorine in 2006.

The Husky refinery will host a community update and open house from 4:30-8 p.m. Tuesday at Superior Middle School, 3625 Hammond Ave. Representatives from the refinery and county, state and federal agencies will be on hand to answer questions and talk about plans for the refinery and health and environmental concerns.